Loader bucket control



Sept. 24, 1968 G. J. GOTH LOADER BUCKET CONTROL Filed Feb. 24, 1967 INVENTOR. Gary J Gail:

ML5o/V, LE, 59761466425? CIFWCT.

United States Patent 3,402,840 LOADER BUCKET CONTROL Gary J. Goth, Rogers, Minn, assignor to J. 1. Case Company, Racine, Wis., a corporation of Wisconsin Filed Feb. 24, 1967, Ser. No. 618,435 4 Claims. (Cl. 214-764) ABSTRACT OF THE DISCLOSURE A bucket is pivotally mounted on a boom to be moved between two extreme positions by a hydraulic bucket cylinder wit-h a second hydraulic cylinder capable of raising and lowering the boom with respect to a vehicle. A valve is interposed in the hydraulic circuit leading to the bucket cylinder with a linkage connection between the bucket, the lift cylinder and the valve so that the valve is automatically closed at a predetermined position of the bucket on the boom while the boom is being raised and lowered to prevent complete bucket roll back at full height of the boom.

Background of the invention The present invention relates generally to material loaders and more particularly to a pivotally mounted bucket with means for automatically maintaining the bucket level to the ground as it is vertically moved with respect to a vehicle.

In material handling vehicles, for example tractor loaders, it is conventional to mount a bucket on a boom which is capable of raising and lowering the bucket with respect to a vehicle. The boom structure carries the pivoted bucket which, when in the lowered position of the boom, engages material as the tractor is driven forwardly and, after the bucket is filled, is capable of being tilted or rolled back on the boom to maintain the contents within the bucket as it is being raised to a position enabling dumping of the bucket to transfer the contents to a vehicle or some other location. As the boom is being pivoted on the vehicle to raise the bucket, it is desirable to maintain the bucket at a predetermined attitude with respect to the ground to prevent spilling of the contents as the bucket is being raised.

In the past, it has been conventional to provide some form of self-leveling means for the bucket for positioning the bucket as it is being raised to a dump position by the boom. Many of the prior art self-leveling devices have incorporated rather elaborate electrical or mechanical components for automatically positioning the bucket on the boom, as it is being raised and lowered thereon. Some of these devices included a manual override to allow the operator to move the bucket to any position relative to the boom if he so desired. This type of arrangement presents a considerable hazard if the operator should inadvertently engage the manual override since this could result in spilling the contents onto the tractor and/or operator and possibly injure the operator and damage the vehicle.

Summary of the invention A primary object of the present invention is to provide an improved mechanism for automatically leveling an implement as it is being moved between two positions.

Another object is to provide a self-leveling bucket control which is automatically capable of compensating for the position of a bucket relative to a supporting vehicle.

A further object is to provide a simple and inexpensive mechanical device which is operable without any attention of the operator.

3,402,840 Patented Sept. 24, 1968 Other objects and features of the invention will become apparent when considered in conjunction with the following specification and the accompanying drawings wherein:

FIGURE 1 is a side elevational view of a tractor loader incorporating the present invention;

FIGURE 2 is a fragmentary view of the inner surface of one boom arm showing the details of the present invention; and

FIGURE 3 is a fragmentary view similar to FIGURE 2 further showing the self-leveling device.

While the invention will be described and illustrated as applied to a crawler tractor loader which has a material handling bucket carried at the free end of pivotally mounted boom arms, it will be appreciated that the invention is not limited to such vehicles and may be applied to any other equivalent type of vehicles having a material handling implement movable thereon.

Referring to FIGURE 1, the illustrated tractor loader 10 includes a conventional tract type vehicle 12 having a frame 14 which pivotally supports a loader 16. The loader 16 includes a bucket 18 pivotally supported at 20 on a pair of boo-m arms 22 having one end pivoted at 24 on the frame 14. The boom or left arms 22 are raised and lowered by a fluid motor 26 having its piston rod carrying a yoke 28 pivoted on the boom arm by a pin 30. The opposite end of the fluid motor 26 is pivotally connected to the frame 14. A compensating or slave cylinder 34 has a piston 35, pivotally connected at 36 to the boom arm 22 while cylinder is interconnected through linkage 38 to the lift cylinder 26. Since the connection between cylinders 26 and 34 is conventional and forms no part of the present invention, a detailed description thereof does not appear to be necessary.

Although only one lift arm 22 and associated elements are shown, it is readily understood that there is another boom arm on the opposite side of the vehicle and the two arms are located symmetrically with respect to a center plane through the vehicle and simultaneously raised and lowered through interconnected fluid motors.

The bucket 18 is adapted to be rotated on the boom arms 22 by a pair of links 40 and 42 respectively having one end pivoted to the bucket 18 and the boom arm 22 and pivotally interconnected at the opposite end. Thus, the links 40, 42 combined with a portion of the bucket 18 and the boom arm 22 form a parallelogram linkage connecting the bucket to the boom arm. Fluid cylinders 44 are pivotally connected to the link 42 and have their piston rods 46 connected to the boom arms 22 through yokes 48. Hydraulic fluid is selectively admitted from a main control valve 50 through a pair of conduits 52 and 54 to ports 56 and 59 located on opposite ends of the fluid motor 44.

During normal operation, the bucket is positioned as shown in FIGURE 1, and the vehicle is advanced until the bucket has been filled. Thereafter, the valve 50 is actuated to direct fluid to port 56 to pivot the bucket 18 on the boom arms 22 tilting the bucket rearwardly to produce a desired break out force and simultaneously move the bucket rearwardly to a level position for raising and subsequent dumping of the bucket. Thereafter, fluid is directed to one end of the lift cylinders or motors 26 to raise the boom arms 22 and the bucket 18 to a height enabling dumping of the bucket so as to transfer the material to some other location. When the lift arms have been raised to the proper height, fluid is admitted through port 58 of pivot motor 44 to move the bucket to the second extreme or dump position.

However, as the arms 22 are being raised, it is important that the bucket be maintained level relative to the ground to avoid spilling the contents during the raising thereof. According to the invention, this is accomplished by valve means in the fluid circuit between the bucket motor 44 and the main control valve 50. In the illustrated embodiment, the valve means includes a valve 70 interposed in the fluid conduit 54 between the control valve and the fluid motor 44. The valve is fixedly secured to the boom arm by brackets 72 and bolts 74. The valve 70 may be a conventional check valve spring biased to a closed position by a spring 75 with a valve stem 76 extending from the housing of the valve. The valve 70 has a support arm 78 fixedly secured thereto which pivotally supports a linkage arm 80 on a pin 82. The arm 80 is in contact with the pin 76 and is normally spring biased by a spring 84 to maintain the valve 70 in the open position. Thus, the combination of the spring 84, arm 80 and the spring 75 within the check valve forms a valve biasing means for maintaining the valve in the open position but allowing it to move to the closed position.

Linkage means are provided for interconnecting the bucket and the arm 80 and the linkage means form a part of the valve biasing means. This linkage means includes a first link having one end pivoted on arm 80 through a pin 92. The free end of the link 90 carries a pin 94 and is connected to a second link 96. The second link 96 is in the form of a telescoping member having a first portion 96a pivoted on the arm 42 with a rod 98 telescopingly received in a tubular member 100 carried by the pivot pin 94.

The link 90 is adapted to be rotated about a pivot point intermediate the ends thereof and, according to another aspect of the invention, the pivot 110 is capable of being moved or displaced in response to the movement of the lift arms with respect to the vehicle. For this purpose, the yoke of the lift cylinder 26 is provided with and integral or fixed lug 112 pivotally supporting a compensating link 114 which has its opposite end connected to the pivot point 110. Preferably, the compensating link 114 includes an adjusting member 116 which can readily be adjusted to vary the effective length of the compensating member 114.

In normal operation, when the boom arms 22 are lowered to the position shown in FIGURE 1, the pivot point 110 of link 90 will be moved towards the check valve 70 by the direct connection between the yoke 28 of lift cylinder 26 and the pivot pin or point 116. This will allow the bucket to be tilted rearwardly or to the rollback position without closing the valve 70. As the boom arms are raised, the pivot pin 110 will be moved away from the check valve 70 an amount corresponding to the relative position of the boom arms. This movement will be suflicient to telescope the member 96 and force the tube 100 into contact with the abutment surface of the member 960. Thereafter, any counterclockwise rotation of the bucket 18 on the boom arms 22 will pivot the link 90 counterclockwise about pivot pin 110 and rotate the arm 80 against the action of the spring 84 thereby closing the valve 70 by the action of the spring within the valve.

With the valve 70 closed, fluid cannot be directed from the main control valve 50 to the port 58. However, simultaneous to extension of lift cylinder 26 fluid will be forced from the head end of the compensating cylinders 32 and will be directed through conduit 52 to the head end of the cylinder or motor 44 thereby extending th piston rod 46 and rotating the bucket 18 clockwise on the boom arms. As the bucket 18 is being rotated clockwise, the telescoping member 96 will be extended allowing the spring 84 to pivot link 90 clockwise about pin- 110 which will open check valve 70. Thereafter, fluid will be directed to port 58 pivoting bucket 18 counterclockwise on boom arms 22.

Of course, this action clockwise and counterclockwise rotation of the bucket will continuously be reversed while the lift arms are being raised to automatically maintain the bucket in a predetermined angular position with respect to the ground. Once the desired height has been reached, the main valve 50 may be operated to supply fluid directly to port 58 rotating the bucket relative to the lift or boom arms 22 to dump contents thereof. During this action, the telescoping member 96 will be extended allowing spring 84 and arm 80 to maintain the valve 70 in the open position.

Thus, it is readily apparent that the invention provides a very simple and inexpensive apparatus for continuously maintaining a bucket at a predetermined attitude with respect to the ground while the bucket is being raised to a dump position. By providing the automatically closing check valve in one of the conduits leading to the bucket or tilt motor, the main control valve 50 may be moved to the roll back position after the bucket has been filled and may remain there until the bucket has been raised to the height where it is to be dumped. This means that the operator cannot rotate the bucket counterclockwise beyond a predetermined position while the boom arms are being raised to move the bucket to the dump position.

While a preferred embodiment of the invention has been shown and described, it will be understood that various changes and modifications may be made without departing from the spirit of the invention as defined by the following claims.

I claim:

1. In a vehicle having an implement movable thereon between two extreme positions and means for moving said implement between said positions including, a fluid motor, a control valve and circuit means for directing fluid between said valve and motor, the improvement comprising valve means in said circuit means, biasing means normally maintaining said valve means open, and linkage means connected to said biasing means and said implement and responsive to movement of said implement for closing said valve means whereby to maintain the implement intermediate the two extreme positions, said linkage means including a telescoping member adapted to allow unrestricted movement of said implement to one of said extreme positions and restrict the movement of said implement to the other of said extreme positions.

2. A vehicle as defined in claim 1, in which said linkage means further includes a centrally pivoted link interconnecting said telescoping member and said biasing means, and means for automatically moving the central pivot of said link in response to a second movement of said implement on the vehicle whereby the intermediate location of said implement is determined by the second movement of said implement.

3. In a vehicle having a bucket assembly pivotally mounted on a boom movable on said vehicle with bucket and boom hydraulic motors for moving said boom with respect to said vehicle and pivoting said bucket on said boom between two extreme positions, a control valve for selectively supplying fluid to said motors and circuit means connecting said valve to said motors; the improvement comprising, valve means in said circuit means to the bucket motor, biasing means normally maintaining the valve means in open condition, and a linkage connection between said bucket and said biasing means responsive to pivotal movement of said bucket to close said valve and locate the implement intermediate said extreme positions, said linkage connection including a link having a pivot point intermediate the ends thereof, a telescoping member for allowing unrestricted movement between the intermediate position and said one extreme position and means for displacing said pivot point in response to movement of said boom whereby said bucket may be moved between said extreme positions when said boom is at a given position relative to said r vehicle.

5 6 4. A vehicle as defined in claim 3, and wherein said References Cited boom is movable between loading and unloading positions by said boom motor and said last means includes a UNITED STATES PATENTS compensating link connected to said boom motor and 2,311,265 10/1957 Wagner 214 763 pivot point to maintain said valve means open when said 5 boom is in the loading position. HUGO O. SCHULZ, Primary Examiner. 

